Here's a few links with ideas:

http://www.entrepreneur.com/businessideas/

http://www.sixmonthmba.com/2009/02/999ideas.html

http://www.ahbbo.com/ideas.html

http://ycombinator.com/ideas.html

http://astartupaday.wordpress.com/

http://www.coolbusinessideas.com/

I've taken all these from a list in the 'Start Small, Stay Small' book here: http://www.startupbook.net/

Good luck!